1. Field of the Invention
The present invention relates to a hybrid vehicle and a method of starting an internal combustion engine mounted on the hybrid vehicle. More specifically the invention pertains to a hybrid vehicle that is drivable with power from an internal combustion engine and with power from a motor, as well as to a method of starting the internal combustion engine mounted on such a hybrid vehicle.
2. Description of the Prior Art
Various techniques have been proposed to start an internal combustion engine during a run of a hybrid vehicle in a drive mode with only power from a motor. One proposed technique accelerates an ignition timing to start the internal combustion engine in response to a driver's acceleration demand, while retarding the ignition timing to start the internal combustion engine without the driver's acceleration demand (see Patent Laid-Open Gazette No. 2001-263213). The hybrid vehicle of this proposed technique starts the internal combustion engine at the accelerated ignition timing, when the driver demands acceleration. This aims at a quick output of power from the internal combustion engine. The hybrid vehicle starts the internal combustion engine at the retarded ignition timing, on the other hand, when the driver does not demand acceleration. This aims at reduction of the potential vibrations arising at the time of starting the internal combustion engine.
The hybrid vehicle is drivable either in a drive mode with only power from the motor or in a drive mode with power from the internal combustion engine. The important issues arising in the process of starting the internal combustion engine during a run of the hybrid vehicle with only the power from the motor are to ensure a quick response to the driver's acceleration demand and to reduce potential vibrations arising at the time of starting the internal combustion engine. In such a hybrid vehicle, the similar issues occur in the process of stopping the operations of the internal combustion engine.